Cucurbitaceae is a plant family commonly known as melons, gourds or cucurbits and includes crops like cucumbers, squashes (including pumpkins), luffas, melons and watermelons. According to Food and Agriculture Organization (FAO, 2002), world production of watermelon exceeded 80 million tons; cucumber exceeded 36 million tons; melon exceeded 22 million tons; and squash exceeded 17 million tons.
A variety of pathogens (virus, fungi, bacteria, nematodes, and insects) affect the productivity of cucurbits (Blanchard et al., 1994 A color atlas of cucurbit diseases, New York: Manson Publishing/John Wiley; Zitter et al., 1996 Compendium of cucurbit diseases, St Paul, Minn., APS Press). Cucurbits are susceptible to many viruses and virus resistance is therefore of major agricultural importance (Provvidenti, 1993, Resistance to viral disease of cucurbits, In Kyle, M. M., ed. Resistance to viral diseases of vegetables, Portland, Oreg., Timber Press, 1993: 8-43).
The taxonomic family Geminiviridae includes some of the most important plant viruses causing severe diseases in agricultural, ornamental and horticultural crops. During the last three decades numerous whitefly-transmitted Begomoviruses, a genus of geminivirus, have emerged as devastating pathogens, particularly in the tropics and subtropics, causing huge economic losses and threatening crop production. Squash Leaf Curl Virus (SLCV), a begomovirus, can cause severe losses in many areas of squash production, but particularly in the major squash growing areas of Mexico, Arizona, California and the Middle East. SLCV was first observed in squash in California during 1977 and 1978 (Flock R A, Mayhew D E., 1981 Squash leaf curl, a new disease of cucurbits in California, Plant Dis. 65:75-76) and in cultivated buffalo gourd in Arizona at about the same time (Rosemeyer et al., 1986 Five viruses isolated from field-grown buffalo gourd, Cucurbita foetidissima HBK, a potential crop for semi-arid lands, Plant Dis 70:405-409).
Current methods of preventing and controlling geminivirus include controlling the spread of insect vectors that carry the virus, developing transgenic plants expressing the viral coat protein, and using classical breeding methods to develop plants having natural resistance to the virus. Disease resistant plants developed using classical plant breeding offer an effective, safe, and relatively less expensive method of controlling many crop diseases. For example, U.S. Pat. No. 7,432,420 describes a squash plant with resistance to SLCV due to a dominant resistance gene in the squash genome.
The present invention provides cucurbit plants, including squash plants, which have an important, useful and alternative form of resistance to SLCV. The resistance of the present invention is imparted by the newly discovered recessive gene slc-2.